Cells to Organs Flashcards
What are tissues?
Tissues contain specialized cells that are similar in structure and perform a common function.
What is homeostasis?
The ability of the body to maintain a constant internal environment regardless of the changes occurring outside the body.
What are the different kinds of tissues found in the body?
- Epithelial
- Connective
- Muscle
- Nervous
Describe epithelial tissue.
- Widespread in the body.
- Forms the covering of all body surfaces.
- Lines body cavities and the surfaces of hollow organs.
- Forms the major tissue in glands.
- Avascular; receives nutrients from basement membrane beneath.
What are the characteristics of basement membrane?
- Contains fibers like collagen.
- Semipermeable
What are the functions of epithelial cells?
- Secretion
- Absorption
- Excretion
- Filtration
- Diffusion
- Protection
- Sensory Reception
Why are epithelial cells said to be polar?
Because they have an apical and a basal end.
What are the different kinds of epithelial tissues based on the number of layers?
- Simple- Single layer
- Stratified- Several layers
What is the difference in function of simple and stratified tissues?
- Simple tissues are found where diffusion takes place.
- Stratified tissues are found where resistance against mechanical and chemical stress is required.
What are the different kinds of epithelial tissues found on the basis of location?
- Membranous- Forms the lining of organs and body surfaces
- Glandular- Forms endocrine and exocrine glands
What are the different kinds of epithelial tissues based on cells?
- Squamous
- Cuboidal
- Columnar
- Transitional- Squamous cells on top, cuboidal beneath
What are the characteristics of squamous tissues?
Simple squamous:
1. Elastic in nature and very thin.
2. Found in air sacs of lungs and blood capillaries.
3. Transfer in waste, nutrients and gases.
Stratified squamous:
1. Forms the layers of skin, mouth and vagina.
2. Protects against abrasion, infection and drying out.
3. Replenishes fast.
What are the characteristics of cuboidal tissues?
Simple cuboidal:
1. Found in glands and kidney tubules.
2. Secretes and reabsorbs water and small molecules.
Stratified cuboidal:
1. Lines ducts of sweat glands.
2. Secretes water and ions.
What are the characteristics of columnar tissues?
Simple columnar:
1. Lines most of the digestive organs.
2. Secretes mucus.
3. Absorbs nutrients.
Stratified/ pseudostratified:
1. Lines epididymis, mammary glands, larynx.
2. Secretes mucus.
Why are pseudostratified columnar tissues named so?
- The cells forming them are incomplete.
- The illusion is given by the positioning of the nuclei which are not leveled properly.
What are the different types of cell junctions?
- Tight junctions- Prevent leaks
- Gap junctions- Connect the cytoplasm of different cells
- Adhering junctions- Cement the cells together.